European Union leaders have reaffirmed their commitment to a landmark deal to limit Iran's nuclear activities in exchange for sanctions relief, despite opposition from U.S. President Donald Trump.

The 28-member bloc gave a nod to concerns Trump has raised, however, by stepping up criticism of Tehran's ballistic-missile program and its role in what the West sees as fomenting instability in the Middle East.

"We fully stay committed to the complete implementation by all sides of the Iranian nuclear deal. We see this as a key security interest for the European Union and the region," the EU's top diplomat, Federica Mogherini, said late on October 19 in Brussels.

The EU leaders issued a joint statement saying, as reported by RFE/RL earlier in the day based on a draft statement, that the EU "reaffirms its full commitment to the Iran nuclear deal."

Since Trump declared his opposition to the 2015 deal and refused to certify Iran's compliance last week, the bloc has been stepping up efforts to save it, and on October 19 appealed to the U.S. Congress not to let it fall apart.

In an address on October 13, Trump asked the U.S. Congress to strengthen a U.S. law related to the deal in order to put additional pressure on Tehran by setting up triggers for the imposition of sanctions.

Trump also said he would seek the removal of so-called sunset clauses, which set expiration dates for some restrictions on Iran's nuclear program under the deal between six global powers and Tehran.

He threatened to withdraw the United States from the deal if his goals are not met, calling on Congress and U.S. allies to help achieve them, and has repeated that threat in subsequent remarks.

Democrats and some Republicans in Congress have said they would not do anything that goes against U.S. allies in Europe, and their statements were noted by officials at the Brussels summit.

"Many Democrats as well as some Republicans feel like they need to play a more active role on foreign policy to restrain the president," one EU official told Reuters.

Still, officials said the EU leaders in their discussions of the deal highlighted the need to protect European companies and investors dealing with Iran from any adverse effects should Washington decide to reinstate U.S. sanctions.

The EU sees the Iran deal as one of the West's biggest diplomatic success stories of recent years. European leaders have expressed concern that the deal's demise would harm efforts to negotiate with North Korea over its nuclear program.

EU foreign ministers earlier this week adopted a statement declaring that the deal is "a key element of the global nuclear nonproliferation architecture and is crucial for the security of the region."

While voicing support for Trump's efforts to curb Iran's ballistic missile program, as well as "concerns" about Iran's role in increasing tensions in the Middle East, European officials said they want to put those disputes on separate tracks from the nuclear deal.

Iran's elite Islamic Revolutionary Guards Corps said on October 19 that despite pressure from the West, Iran will accelerate the ballistic missile program, which it views as critical for self-defense, the semi-official Tasnim news agency reported.

With reporting by AP, Reuters, and RFE/RL's Rikard Jozwiak in Brussels